The Heparin form a complex with a plasma protein, antithrombin III (ATIII), which is an endogenous anticoagulant. This complex inhibits the formation of thrombin and accelerates its destruction. Moreover, heparin and other proteases ATIII inactivate the clotting cascade, especially the anti-activated factor X. The end result of these actions is the inhibition of biochemical training and synthesis of certain clotting factors that activators of critical functions in the genesis of a blood clot. Patients with chronic renal failure (CRF) who use the treatment of hemodialysis need a system of anticoagulation with the direct thrombin inhibitor and / or heparinóides to prevent thrombosis.